7.3. Virtualization Hosts

7.3.1. Sizing Guidelines for Oracle VM VirtualBox Servers

We found that the 'VMs/core' unit, while being striking, is a
fuzzy statement as the available CPUs today differ by at least a
factor of 2 in performance and that even ignores older CPUs
customers may want to reuse. Therefore we decided to also
provide the 'SPEC CINT2006 Rate (peak) / VM' value. Statements
made based on this unit are valid for a longer time as they
abstract from a concrete CPU, while statements based on
'VMs/core' hold true for cores showing roughly the same
performance only.

The numbers for this section have been updated based on a new
test run. We were able to run 100 VMs on a X4170 with two E5520
CPUs having 4 cores each. The SPEC CINT2006 Rate (peak) for
servers with two E5520 CPUs is ~200 which results in a cint / VM
value of 2.

Number of cores = number
of running desktops / 12.5

Example: A server roughly equivalent to a X4170 with two
E5520 CPUs can support up to 2 x 4 x 12.5 = 100 running
desktops